Lorentz-violating vs. ghost gravitons: the example of Weyl gravity

Abstract : We show that the ghost degrees of freedom of Einstein gravity with a Weyl term can be tamed by a simple mechanism that invokes local Lorentz symmetry breaking. We demonstrate how the mechanism works in a cosmological setting. The presence of the Weyl term forces a redefinition of the quantum vacuum state of the tensor perturbations. As a consequence the amplitude of their spectrum blows up when the Lorentz-violating scale becomes comparable to the Hubble radius. Such a behaviour is in sharp contrast to what happens in standard Weyl gravity where the gravitational ghosts smoothly damp out the spectrum of primordial gravitational waves.
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Journal articles
Journal of High Energy Physics, Institute of Physics (IOP), 2012, 09, pp.009. <10.1007/JHEP09(2012)009>


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Contributor : Alina Deniau <>
Submitted on : Wednesday, October 10, 2012 - 6:35:40 PM
Last modification on : Tuesday, October 28, 2014 - 6:18:29 PM

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N. Deruelle, M. Sasaki, Y. Sendouda, A. Youssef. Lorentz-violating vs. ghost gravitons: the example of Weyl gravity. Journal of High Energy Physics, Institute of Physics (IOP), 2012, 09, pp.009. <10.1007/JHEP09(2012)009>. <hal-00740758>

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